/*
 * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include "onewire_crc.h"

#define FAST_CRC 1 // define this to use the fast CRC table

#if FAST_CRC

static const uint8_t dalas_crc8_table[] = {
    0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
    157, 195, 33, 127, 252, 162, 64, 30, 95,  1, 227, 189, 62, 96, 130, 220,
    35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93,  3, 128, 222, 60, 98,
    190, 224,  2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
    70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89,  7,
    219, 133, 103, 57, 186, 228,  6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
    101, 59, 217, 135,  4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
    248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91,  5, 231, 185,
    140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
    17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
    175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
    50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
    202, 148, 118, 40, 171, 245, 23, 73,  8, 86, 180, 234, 105, 55, 213, 139,
    87,  9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
    233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
    116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
};

uint8_t onewire_crc8(uint8_t init_crc, uint8_t *input, size_t input_size)
{
    uint8_t crc = init_crc;
    for (size_t i = 0; i < input_size; i ++) {
        crc = dalas_crc8_table[crc ^ input[i]];
    }
    return crc;
}

#else // FAST_CRC

uint8_t onewire_crc8(uint8_t init_crc, uint8_t *input, size_t input_size)
{
    uint8_t crc = init_crc;
    for (size_t i = 0; i < input_size; i++) {
        uint8_t byte = input[i];
        for (int j = 0; j < 8; j++) {
            uint8_t x = (byte ^ crc) & 0x01;
            crc >>= 1;
            if (x != 0) {
                crc ^= 0x8C;
            }
            byte >>= 1;
        }
    }
    return crc;
}

#endif // FAST_CRC
